The approaches described in this section could be pursued, but are not necessarily approaches that have been previously conceived or pursued. Therefore, unless otherwise indicated herein, the approaches described in this section are not prior art to the claims in this application and are not admitted to be prior art by inclusion in this section.
Prior to the invention of videotape in the 1960s, the only way to preserve a live television broadcast, such as broadcasts using signals conforming to standards of the US National Television Standards Committee (NTSC), was to make a motion picture film copy of the program utilizing a kinescope recording machine, which comprised a synchronized movie camera and television monitor combination. In effect, the TV program was filmed off a monitor, as the program was broadcast live. Kinescopes were widely used to make filmed copies of broadcasts from about 1940 to about 1965. Thus, in many cases kinescopes are the only record of culturally or historically important television broadcasts of the 1940s, 1950s, and early 1960s.
Although this approach preserved the program, the filmed copy of the broadcast was considered by both viewers and technicians alike to be noticeably inferior to the original program transmission. The reason for viewers and technicians to perceive the filmed copy as inferior may lie in the differences of frame rates of the television program and the film camera. A live NTSC television signal broadcasts at approximately 30 frames per second (fps). Typically, a kinescope film camera used to record the broadcast operated at about 24 fps. Therefore, filming the broadcast theoretically resulted in an automatic 16% loss of motion, because the shutter of the kinescope film camera would be closed during (30-24)=6 of 30 frames of each second of the television broadcast.
Further analysis of this problem shows that the actual loss was much greater than 16%. What viewers and technicians term one “frame” of an NTSC broadcast technically comprises two interleaved half-frames taken 1/60 of a second apart. Hence, an NTSC signal does not comprise 30 static frames per second; the signal actually comprises 60 unique and dynamic half-frames, which are designed to interleave in 30 pairs per second.
The use of a rate of 60 fps, in combination with the characteristic of the human eye termed “persistence of vision,” provides a perception of natural motion in an NTSC broadcast signal. Further, the fact that NTSC broadcasts use 60 fps is why kinescopes, or any film that is broadcast over an NTSC system, has a flickering, jittery quality of motion, when compared to live action or videotape. Such kinescopes or films do not comprise enough unique frames per second to give the illusion of natural motion or to accurately reproduce all 60 fps of an NTSC television signal. Film can only provide 24 of the needed 60 images per second.
However, historians, broadcasters, and others are interested in bringing historic television programs back to the screen, if the historic programs can be shown with quality that is acceptable to the contemporary viewer. Merely broadcasting a video transfer of a kinescope results in a program of unacceptable motion quality for the typical viewer. Based on the foregoing, there is a clear need for an improved approach for processing kinescopes, other filmed copies of television broadcasts, and other motion picture film, prior to re-broadcast with contemporary equipment.